Probably the biggest draw of the Elm Bank workshop on September 10, 2009, was Mike Furgal’s moving of a 6″ caliper elm hybrid. Mike first developed the method of air-tool bare-root transplanting in 2004, and has been working on it since, moving ornamental specimens and canopy trees with great success. The biggest tree he has moved was a 21″ caliper, 50′ high mulberry (it was the owner’s choice), in November 2008; this past July he worked on Matt Foti’s project of moving several large trees, including the five 40′ high London plane trees showcased in posts on www.takingplace.net.

(To find those posts, click on the link in the last sentence, and then click on the ‘Plants’ link in Categories listed on the right side of the page. All posts related to air-tool transplanting will pop up; the links for the London plane project are dated July 29, July 31, August 3, and August 7. Browse among earlier ‘Plants’ posts for more articles on bare-root transplanting.)

So Mike has lots of experience with this work, and continues to think about the best ways — for the trees and for the crews — to move trees. He made a number of observations in his Elm Bank talk about air-tool transplanting:

1. The larger the tree, the more cost-effective the bare-root move is.

2. Bare-root transplanting lets roots settle immediately into the soil on the new site. With no root ball/surrounding soil interface to impede moisture saturation or interrupt moisture flow, the roots are able to adapt right away and start growing. As a result, watering and aftercare are also easier and more effective.

3. The greater the depth of good quality soil, the more apt roots are to grow down as well as out.

4. Arborists and landscape architects MUST stress the need for sustained aftercare once a tree has been bare-root transplanted. One year of attentive watering is good, but two, three, four, or even five years is better.

5. Mike asked “Do we arborists plant trees or do we install them?” When you install a B&B tree, he suggested, you dig a hole, put the tree in the ground, backfill, and water. When you plant a tree, you remove the wire basket, remove the burlap and twine, possibly break up the soil mass, spread the roots out to promote outward growth, and water sufficiently for the next couple of years for the tree to root into its home. ‘Installing’ a tree makes the tree simply a product, a commodity that can (and may have to be) replaced. ‘Planting’ a tree recognizes and attends to the needs of this living organism, and promotes its good health and sustained long life.

6. Air tools dry out root surfaces — pre-watering of the root mass and soil around a tree to be moved helps the tree hydrate and maintain turgor pressure during the transplant operation. Mike suggested that trees may have a greater tolerance for short-term root drying than is commonly assumed, and urged the audience to observe what happens to the roots of trees they may move bare-root, and how those trees react to the process.

7. When you use an air tool to excavate a tree for transplanting, dig your soil trench in sections, and dig it deep enough (measured in feet, not inches) to hold quite a bit of blown out soil, thus minimizing the number of times it needs to be emptied. Mike pointed out that it’s necessary to consider how best to move the excess soil around; it’s important to plan the job at the outset, including how to access the plant(s) to be moved, how to avoid plants to remain, and where to stockpile the blown-out soil.

8. The bare-root process can allow arborists use lighter equipment (depending on tree size, of course) than may be necessary for B&B trees. A 2000-pound mini-excavator can pick up a six-inch elm, while to move that same tree B&B would require a large backhoe or front-end loader.

9. The more fibrous a tree’s root system, the less likely it is to need cabling after a bare-root transplant. A root mass’s size, the nature of its rooting, and the relationship between those factors and the tree’s size will also factor into the decision to cable a newly-planted bare-root tree.

Mike had blown soil out from around the roots of the Elm Bank elm the day before the workshop, and kept them covered until the workshop demonstrations began.

Healthy elm tree, soil blown off its roots, ready to be moved.

Closeup of the roots. This root mass measured 14 feet across at its widest. Roots have been pigtailed -- that is, tied together and lifted to keep them from breaking during the air-tool excavation and move.

Dingo used to move the tree, whose new location was about fifty feet away from where it originally stood.

Mike Furgal and his assistant planning their course of action. Note the tagline leading out from the canopy; it will be used to stabilize the tree during the move and backfill operation.

Mike directs the Dingo forks under the root plate while his assistant holds the trunk stable. Note the heavy burlap padding both on the Dingo and on the tree trunk.

Beginning to move the tree requires that it sit firmly on the forks, and remain balanced through the move.

Cutting the last few anchored roots, and any roots broken in the process. Loppers work best; be sure they are sharp enough to make clean cuts (a set of root-pruning tools is useful, as cutting dirty roots with top-growth tools will ruin their blades quickly).

Moving the elm up its soil ramp and out of its plant bed; an attending arborist jumps in to help the roots past this thriving pine.

Elm tree on the move. Stabilizing the trunk and moving slowly keeps the job safe.

Big canopy. This year's growing season was moist and fairly cool, leading to lots of topgrowth and long twig extension.

Mike steers the Dingo to the crater he has dug. It is relatively shallow, to match the elm root mass depth, and wide (though not wide enough at first -- a couple of trenches had to be dug beyond the crater at the last minute to some extra-long roots).

Lowering the elm into its crater.

Whoa! A moment of excitement, when tree weight and crater's-edge slope combined to tip the Dingo on its tracks.

The Iwo Jima shot. A team of volunteers ran in to right the tree.

Holding the tree upright once the Dingo forks have been pulled out.

Again, holding the tree upright. The pigtails now get cut open and roots spread out radially from the trunk.

Freeing the roots, beginning to dig in backfill, and watering to make a soil slurry that will eliminate air pockets and help anchor the spread-out root plate.

With the tree in its new location, burlap padding the trunk may be removed.

Digging in the root mass. It's important to pack the soil directly under the tree's trunk, to eliminate air holes and ensure against settling of the tree lower in its hole over time.

Big canopy on this tree, with a root mass to match.

A bucket on the Dingo shakes backfill -- the native soil onsite in this case -- into the crater as workers wield shovels and a hose.

More backfill, more water, and someone still holds the tagline for safety. The Dingo never drives over the root mass, but drops soil onto it from outside the planting hole.

Still more water, as the backfilling continues.

Building the well wall, as water continues to flow.

Six-inch caliper elm tree in its new location. Some wilt is evident -- likely because the tree was excavated the day before and the roots had been exposed through the course of the several-hours long workshop. The tagline finally lies slack. Two to four inches of mulch will next be added, and kept away from the trunk.

At the MAA Elm Bank workshop on September 10, 2009, Matt Foti demonstrated how to address root problems at the time of planting. He had a fairly large collection of trunk-and-root masses to illustrate his points, and used them to show how girdling roots, secondary root systems, and J-rooted systems can develop as a result of poor planting or growing practices.

Matt first showed a couple of forest saplings he had pulled early in the day to illustrate how a naturally-seeded tree’s roots grow. The sapling’s roots were evenly spaced around its stem, and extended out a distance relatively equivalent to the distance its topgrowth extended from the stem.

He then pointed to a couple of nursery-grown trees whose rooting problems had become evident after several years.

These root systems have been cut in the digging process. In an attempt to regrow roots, the foreground tree has sent out a secondary root system, several of which are beginning to girdle other roots. Kept too long in a burlapped ball or in a container, roots will often turn back in to the ball, making effective planting and long-term growth problematic.

Shrubs as well as trees are susceptible to root problems; Matt dismantled an Ilex verticillata root mass to illustrate how he treats roots bound in a container or in burlap before planting.

Fibrous roots hold together in a near solid mass right out of the container.

Using a three-pronged fork to untangle the root mass. For a bigger shrub or small tree, a machete or pitchfork may work well to loosen soil and reorient roots.

Ilex verticillata root mass, now ready for planting.

Soil can present another problem for nursery-dug B&B trees. Clay soils make sturdy root balls, which can be useful for shipping, but not so great for root growth.

This pair of trees have root masses encased in rock-hard clay soils. Note the solid clumps of clay in the foreground, and root growth only on top of the root ball -- these roots found it impossible to grow into and through this soil. Breaking up the soil in a root ball like this before planting promotes the tree's future health; leaving this kind of root ball intact almost guarantees tree stress and decline.

Another example of a dense clay root ball that constricted root growth to the tree's great detriment. Soil had also been piled up around this tree's trunk flare, further challenging its ability to live. Tough conditions for a tree to grow in...

The point of these illustrations was to show how necessary it is, when planting a tree or shrub, to work with the root ball before covering it with soil. Removing wire baskets, removing burlap, loosening or removing the soil, untangling roots as best as possible, pruning roots when necessary — all these tactics make up a strategy for promoting real tree growth. Bare-root techniques have shown that a great deal of the work that arborists do these days is remedial — that is, is work intended to remedy poor growing, digging, or planting practices. With the knowledge arborists now have of how root issues so obviously affect plant health, it only makes sense to attend to those issues early on, to avoid greater problems later.

Tree Specialists manned the decompaction station at the MAA workshop on September 10, 2009. Standing between two mature sugar maple trees, Rolf Briggs used a compaction meter (from Forestry Suppliers, Inc.) to show how thoroughly compacted the soil around these trees was (very).

Again, the arborists set up barriers to limit the area affected by blown-out soil and pebbles. Rolf Briggs (right foreground) showed how to use a compaction meter, and explained that the green flags delineate the area to be decompacted. Flagging the area for review by the client makes the limit of work clear to all parties.

Compaction limits the movement of moisture and of gases (oxygen included) in soils, and so can create significant problems for trees. Trees rely on water being available to their roots, and on the ready intake of oxygen (from the air and from water molecules) for carbon dioxide discharged by those roots. Compacted soils tend not to allow oxygen in in sufficient quantities, nor allow the steady release of carbon dioxide that a tree needs. Breaking up the compaction, adding organic amendments to improve soil structure, and replacing lawn areas around trees with mulch beds are steps that benefit soil health, and as a result, tree health.

Decompacting soil around two sugar maple trees. One man operates the air tool, blowing vertical trenches and mixing their backfill with a proprietary organic soil amendment that mimics forest duff. The other operator mans the air hose, and tugs on it to signal to the operator. Air tools are loud!. Green flags indicate limits of the decompaction zone.

Tree Specialists prewaters the work area 24-48 hours before starting on a decompaction project, to hydrate the roots and help keep dust down. As they proceed with the process, they begin to ‘fold in’ amendments.

For further information on decompaction, Briggs recommended an article in the current issue (September 2009) of Tree Care Industry Magazine on soil decompaction and amendment.

The Massachusetts Arborists Association workshop on September 10, 2009, took place on a sunny, cool day at the Mass. Hort. Society’s headquarters at Elm Bank in Wellesley, MA.

Quite a few arborists and other landscape professionals attended the workshop, which began with slide talks and then moved outside to field demonstrations.

This workshop focused on root issues, with demonstrations of what some of those issues are — conflicts with utility lines, the effects of poor growing and planting practices, decline due to compacted and poor soils, and inappropriate tree locations — and how they may be remedied.

Rolf Briggs and Tree Specialists set up shop at a couple of different stations to show how they use air tools both to decompact soils and to excavate utility trenches near trees. The demonstrating arborists first discussed protective equipment, and showed what they use when they employ air tools: We watched as they put on respirators, helmets with face masks, ear protection, gloves, and either foul weather gear or jumpsuits — all necessary to protect from the great quantities of dust, soil, and stones blowing into the air.

To protect the surrounding area from flying detritus, Mike Hickman of Tree Specialists set up plywood or screen barriers around his work zone. I’ve seen plain plywood sheets used; the Tree Specialist guys have figured out that hinging several sheets together makes for a sturdier barrier, a good thing if you’re using air tools with any regularity in anything but a wide-open landscape.

Hinged plywood panels keep the dust contained to the area around a trench.

When it's necessary to dig a trench near a tree, air tools can do the job while preserving the tree's roots. You can see roots crossing this trench, but plenty of space beneath them for a new conduit or line. This trench was blown out with an air spade, and rocks and excess loose material after the blowing-out removed by hand.

The power of compressed air will break up soil move it out of the way; it can also damage roots to some extent, by blowing root bark or feeder roots entirely away. When using an air tool, experienced operators keep the nozzle moving to limit this kind of damage, and whenever possible (definitely not always possible in trenching work), they direct the air flow parallel to the direction of major root growth, away from the base of the tree.

Note the plywood barrier inside the trench as well, to focus the air blast and prevent soil from blowing into a previously blown-out section.

Blowing out the trench. This air tool is a new product that uses an auxiliary stream of water to help keep the roots hydrated and the dust down. Tree Specialists is assessing this new feature.

After blowing out a utility trench, Tree Specialists simply returns the native soil to the excavated area. They may add some amendments such as lime or humates, if they have already had soil tests done that indicate the need for such amendments. And to mulch the area once excavation and backfilling are complete, they have developed a proprietary mix of chipped and composted wood fibers (mainly from tree parts 3″ and less in diameter), twigs, and leaves. They use this same mix in their soil decompaction process, and note benefits to the trees from its use.

Mike Hickman pointed out that air tools break down soil aggregates and so obliterate soil structure in the area blown out. This breakdown can be considered a disadvantage of using compressed air for excavation; in Mike’s words, “Destruction of some of the soil aggregates I see as a “con,” but proper horticultural practices such as mulching and site specific amendments effectively mitigate these cons.”

Yesterday the Massachusetts Arborists Association held a day-long workshop at Elm Bank, headquarters for the Massachusetts Horticulture Society in Wellesley, MA. Three arborists — Dave Leonard from Kentucky, Rolf Briggs of Holliston, MA, and Matt Foti of Lexington, MA — spoke about particular root issues; Mike Furgal, from Northborough, MA, discussed the use of air tools in bare-root tree transplanting. After hearing the talks, the hundred or so attendees split into groups and visited five stations on the Elm Bank grounds where the featured speakers were giving demonstrations on their topics.

It was a fine workshop, and I’ll be posting quite a few photos from it in the next few days. Today, though, I’m only posting this photo:

Sugar maple whose trunk flare was excavated several years ago at a Bartlett Tree workshop given to demonstrate the new and revolutionary use of air tools in tree work.

Several years ago, I went with a friend to this Bartlett Tree workshop at Elm Bank, and we were among a smallish group who watched as an arborist blew several inches of soil away from the trunk flare of this Sugar Maple. As I recall, the tree had been planted a bit deep, it was set in a fairly compacted lawn, and it was not looking as well as it might; at the time (this was perhaps seven or eight, or perhaps even ten years ago) it had about a six-inch caliper trunk and was not thriving.

Now, however, the tree looks really good. It may have a little too much mulch around its base — built up since its excavation — but its foliage is deep green, its bark is intact (trunk injuries sometimes show up as a result of some kind of root trauma or injury), and it certainly has grown. A mulch bed surrounds it and keeps lawnmowers away as it minimizes compaction. If this kind of growth results from attending to root issues early on and from maintaining a tree properly, the arborists from this workshop may prove, down the road, to be responsible for promoting what truly may be the best arboricultural practices around.